Schneider Barbara St Pierre, Fine Jason P, Nadolski Timothy, Tiidus Peter M
University of Wisconsin-Madison School of Nursing, Clinical Science Center, Room K6/364, 600 N. Highland Avenue, Madison, WI 53792-2455, USA.
Biol Res Nurs. 2004 Apr;5(4):265-75. doi: 10.1177/1099800403262258.
The aim of this study was to examine specific and interactional effects of estradiol and progesterone on the time-to-fatigue of eccentrically contracted plantarflexor muscles and on the percent of plantarflexor isometric torque remaining immediately after an eccentric contraction (EC) protocol. Ovariectomized 6- to 8-week-old C57BL/6 mice were implanted with 21-day 0.05 mg-placebo, 0.05 mg-17-beta estradiol (OE), 15 mg-progesterone (OP), or estradiol and progesterone pellets (OEP). On the 16th day of hormone treatment, the isometric torque of the left plantarflexor muscles was measured. The left plantarflexor muscles then underwent 1 set of 150 ECs followed by 2 immediate post-EC isometric torque measurements. A group of ovarian-intact female mice of a similar age underwent the same isometric torque measurements and EC protocol. Plantarflexor muscle fatigue during ECs took 30%-41% longer to occur in the OP group (n = 9) than it did in the intact (n = 8, P = 0.02), OC (n = 11, P = 0.003), and OEP (n = 9, P = 0.007) groups. Peak active isometric torque had decreased immediately after ECs at 2 time points (M1 and M2). The OP group exhibited the greatest percent of isometric torque remaining immediately after ECs (M1, P = 0.03; M2, P = 0.04). These findings suggest that progesterone reduces muscle fatigue in response to ECs and that this progesterone effect is blunted when estradiol also is present. Therefore, ovarian hormone status may need to be considered when evaluating a response to physical activities, especially those activities involving ECs.
本研究的目的是考察雌二醇和孕酮对离心收缩的跖屈肌疲劳时间以及离心收缩（EC）方案后立即剩余的跖屈肌等长扭矩百分比的特定作用和相互作用。对6至8周龄的去卵巢C57BL/6小鼠植入21天的0.05毫克安慰剂、0.05毫克17-β雌二醇（OE）、15毫克孕酮（OP）或雌二醇和孕酮丸剂（OEP）。在激素治疗的第16天，测量左跖屈肌的等长扭矩。然后左跖屈肌进行一组150次EC，随后立即进行2次EC后等长扭矩测量。一组年龄相似的未去卵巢雌性小鼠进行相同的等长扭矩测量和EC方案。与完整组（n = 8，P = 0.02）、OC组（n = 11，P = 0.003）和OEP组（n = 9，P = 0.007）相比，OP组（n = 9）在EC过程中跖屈肌疲劳发生的时间长30%-41%。在两个时间点（M1和M2），EC后峰值主动等长扭矩立即下降。OP组在EC后立即剩余的等长扭矩百分比最高（M1，P = 0.03；M2，P = 0.04）。这些发现表明，孕酮可减轻EC引起的肌肉疲劳，且当同时存在雌二醇时，这种孕酮作用会减弱。因此，在评估对体育活动的反应时，尤其是那些涉及EC的活动时，可能需要考虑卵巢激素状态。
